Aad G.Abbott B.Abeling K.Abidi S. H.Aboulhorma A.Abramowicz H.Abreu H.Abulaiti Y.Hoffman A. C. AbuslemeAcharya B. S.Bourdarios C. AdamAdamczyk L.Adamek L.Addepalli S. V.Adelman J.Adiguzel A.Adorni S.Adye T.Affolder A. A.Afik Y.Agaras M. N.Agarwala J.Aggarwal A.Agheorghiesei C.Aguilar-Saavedra J. A.Ahmad A.Ahmadov F.Ahmed W. S.Ahuja S.Ai X.Aielli G.Tamlihat M. AitAitbenchikh B.Aizenberg I.Akbiyik M.Akesson T. P. A.Akimov A. V.Al Khoury K.Alberghi G. L.Albert J.2025-05-192025-05-192023/12/100370-2693http://dx.doi.org/10.1016/j.physletb.2023.138292https://publicacionesabiertas.userena.cl/handle/123456789/228Searches for the exclusive decays of the Higgs boson to an omega meson and a photon or a K* meson and a photon can probe flavour-conserving and flavour-violating Higgs boson couplings to light quarks, respectively. Searches for these decays, along with the analogous Z boson decay to an omega meson and a photon, are performed with a pp collision data sample corresponding to integrated luminosities of up to 134 fb(-1) collected at root s = 13 TeV with the ATLAS detector at the CERN Large Hadron Collider. The obtained 95% confidence-level upper limits on the respective branching fractions are B(H -> omega gamma) < 5.5 x 10(-4), B(H -> K*gamma) < 2.2 x 10(-4) and B(Z -> omega gamma) < 3.9 x 10(-6). The limits for H -> omega gamma and Z -> omega gamma) are 370 times and 140 times the Standard Model expected values, respectively. The result for Z -> omega gamma corresponds to a two-orders-of-magnitude improvement over the limit obtained by the DELPHI experiment at LEP.HIERARCHYArticle